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Physics Data Processing - The online connection

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This presentation contains an overview of my work at Nikhef, the Dutch national institute for subatomic physics, in the last few years.

This presentation contains an overview of my work at Nikhef, the Dutch national institute for subatomic physics, in the last few years.

Published in: Career, Technology, Business

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  • 1. Physics Data Processing -The online connection
    Nikhef colloquium
    9/2/2009
    Sander Klous
  • 2. The steamboat view
    PDP Activities
    Bob Hertzberger
    2
    Physics Data Processing - Sander Klous
    9/2/2009
    Remote Online Farms
    Use Cases (i.e. trigger performance)
    My focus
  • 3. Remote Online Farms
    What is a remote online farm?
    The connection to the online system
    Event routing and streaming
    Remote online farms in ATLAS (Hegoi Garitaonandia)
    Debug stream reprocessing
    Trigger menu validation
    Muon calibration stream
    Do we really need remote online farms?
    9/2/2009
    Physics Data Processing - Sander Klous
    3
  • 4. Concept
    Physics Data Processing - Sander Klous
    4
    Data Acquisition
    40 MHz
    Level 1
    Level 2
    Level 3
    Amsterdam
    Accept 1 in 500
    NIKHEF/SARA
    Network
    switch
    Accept 1 in 50
    Accept 1 in 10
    Computing grid
    9/2/2009
  • 5. Why is this interesting?
    9/2/2009
    Physics Data Processing - Sander Klous
    5
    January 2001
    Gary Stix, editor of Scientific American
  • 6. Connection to the online system
    9/2/2009
    Physics Data Processing - Sander Klous
    6
    ROF
    ROF
    ROF
    ROF
    EF
    SFO
    Remote Event Processing Farms
    ROB
    ROB
    ROB
    ROB
    Data Collection Network
    Packet
    Switched
    (GEANT)
    SFI
    SFI
    SFI
    Routing and Streaming
    Level 2 Trigger
    Light path
    Back End Network
    L2PU
    Event Filter
    Mass
    storage
    Building 513
    CatalinMeirosu
    DDM
    Local Farm
  • 7. Routing and Streaming introduction
    9/2/2009
    Physics Data Processing - Sander Klous
    7
    Hans von der Schmitt
    Optimizing resources
    Online, different routes
    Offline, different streams
    Classification of events
    Physics
    Calibration
    Debug
    Express
    Remote
  • 8. Regions of Interest andPartial Event Building
    9/2/2009
    Physics Data Processing - Sander Klous
    8
    Virtual Point 1
    Ignacio Aracena
  • 9. Inclusive or Exclusive streaming
    9/2/2009
    Physics Data Processing - Sander Klous
    9
    Hans von der Schmitt
  • 10. Online monitoring of overlaps
    9/2/2009
    Physics Data Processing - Sander Klous
    10
    Brian Petersen
  • 11. Luminosity blocks
    9/2/2009
    Physics Data Processing - Sander Klous
    11
    Hans von der Schmitt
  • 12. Final Dress RehearsalData Quality Monitoring
    DDM/DQ2
    TIER-0
    RAW
    320
    TIER-1s
    320
    ESD
    720
    200
    200
    200
    CASTOR
    AOD
    200
    720
    TAG
    440
    Luc Goossens
    CPU farm
    Data
    acquisition
    TAG
    DB
    disk
    150TB
    1060
    raid
    25TB
    load TAG
    320
    130
    recon EXPR
    340
    online
    SFO
    recon PHYS
    T0M
    DB
    c1
    Cond
    DB
    calib/align
    c1
    Express stream handling
    9/2/2009
    Physics Data Processing - Sander Klous
    12
    Rates in MB/s
  • 13. Debug stream reprocessing
    9/2/2009
    Physics Data Processing - Sander Klous
    13
  • 14. Trigger menu validation
    9/2/2009
    Physics Data Processing - Sander Klous
    14
  • 15. Muon calibration
    9/2/2009
    Physics Data Processing - Sander Klous
    15
    MuonCalibrationGroup
    Virtual Point 1
  • 16. Do we really need ROFs?
    At the moment: No, not really…
    Not for physics at least
    Transition will be gradual
    Example: debug stream reprocessing
    Limited resources in the CERN Analysis Facility
    Funding will play an important role
    Easier to fund online resources in home country
    Other factors: energy consumption, human resources
    What will be the first physics use case?
    9/2/2009
    Physics Data Processing - Sander Klous
    16
  • 17. Trigger performance
    Fully Hadronic decays of top pairs
    The jet trigger challenge
    Determining trigger efficiencies from data
    Tag and probe with leptons
    T&P with semi-leptonic decays of top pairs(Menelaos Tsiakiris)
    Turning the probe around, T&P with jets
    Jet trigger efficiencies and rates
    Beyond multi-jet triggers
    Topology triggers and remote online farms
    9/2/2009
    Physics Data Processing - Sander Klous
    17
  • 18. Fully Hadronic decaysof top-antitop pairs
    9/2/2009
    Physics Data Processing - Sander Klous
    18
  • 19. The jet trigger challenge
    QCD 6 jet background
    1000 to 10000 x Signal
    Is this possible at all?
    Long term study
    First look at semi-leptonic decays
    Study the possibility to trigger on jets
    Extract jet trigger efficiency from data
    Cross correlate with muon triggers
    9/2/2009
    Physics Data Processing - Sander Klous
    19
    Turn on kicks in.
    Trigger problem
    Lambacher
    Munich
    O(1 fb-1)
  • 20. Trigger efficiency from data
    20 GeV muon turn on curve (CSC note)
    Tagged
    Tagged and Probed
    Tag and probe
    A first example:di-muon decays of Z bosons
    9/2/2009
    Physics Data Processing - Sander Klous
    20
  • 21. Semi leptonic decays of top pairs
    Tag on the jet side and probe on the muon side
    Extract number of signal events (1 fb-1)
    Invariant mass reconstruction on hadronic side
    9/2/2009
    Physics Data Processing - Sander Klous
    21
    Possible problem: contamination with tau to muon decays
  • 22. Event by event trigger efficiency
    Determine individual object efficiencies
    Extrapolate T&P from di-muon decays of Z-bosons
    Combine objects into an event efficiency
    Weigh the event appropriately
    9/2/2009
    Physics Data Processing - Sander Klous
    22
    Correct isolation withrespect to closest jet
    Correct foreta dependency
    Without corrections
    Tamsett – Royal Holloway
  • 23. Turning the probe around
    More complicated
    The jets are multi-object triggers,e.g. 4J_95: 4 jets above 95 GeV
    Thresholds are likely to change
    The missing link:
    Trigger efficiency of Semi Leptonic decays
    Fully Hadronic decays of top quark pairs
    Is it possible?
    If not, can we do better?
    9/2/2009
    Physics Data Processing - Sander Klous
    23
  • 24. Topology triggers and remote online farms
    Topology triggers
    Time consuming
    Invariant masses
    Likelihood fits
    Budget in point 1
    1500 machines x 8 cores per machine = 12000 cores
    3 kHz EF input rate from LVL2
    12000 / 3000 = 4 seconds per event (all triggers)
    9/2/2009
    Physics Data Processing - Sander Klous
    24
    Xin Wu
    Event Filter
    Mean: 1.57 seconds
    (Erik van der Kraaij)
  • 25. Conclusion
    Remote Online Farms
    An interesting research topic
    Several farms already in production
    Still far from enabling grid for online processing
    Physics Use Cases
    Most likely complicated topologies
    Fully hadronic decays of top quark pairs
    Studies ongoing to understand trigger efficiencies
    The future of grid is in the online connection
    9/2/2009
    Physics Data Processing - Sander Klous
    25

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